Phase III Study of Edasalonexent in Boys With Duchenne Muscular Dystrophy

The study includes a 52-week, randomized, double-blind, placebo-controlled period, followed
by a 2-week follow- up. Approximately 125 boys with DMD will be enrolled in this trial, with
2 boys receiving edasalonexent for every 1 boy receiving placebo.

Following completion of the treatment period, patients may elect to continue in a separate
open-label extension study.

Inclusion Criteria:

- Written consent/assent by patient and/or legal guardian as per regional and/or
Institutional Review Board (IRB)/Independent Ethics Committee (IEC) requirements

- Diagnosis of DMD based on a clinical phenotype with increased serum creatine kinase
(CK) and documentation of mutation(s) in the dystrophin gene known to be associated
with a DMD phenotype

- Able to perform stand from supine without assistance in ≤ 10 seconds

- Able to perform the 10MWT and 4-stair climb

- Followed by a doctor or medical professional who coordinates Duchenne care on a
regular basis and willingness to disclose patient's study participation with medical
professionals

Exclusion Criteria:

- Use of corticosteroids within 24 weeks prior to Day 1; use of inhaled, intranasal, and
topical corticosteroids is permitted

- Use of another investigational drug, idebenone, or dystrophin-focused therapy within 4
weeks. Exception: Patients who have received at least 24 weeks of a stable dose of
eteplirsen prior to Day 1, and expected to continue treatment, will be eligible

- Use of the following within 4 weeks prior to Day 1: immunosuppressive therapy,
warfarin, phenytoin, S mephenytoin, cyclosporine, dihydroergotamine, ergotamine,
fentanyl, alfentanil, pimozide, quinidine, sirolimus, tacrolimus, or paclitaxel

- Use of human growth hormone within 3 months prior to Day 1

- Other prior or ongoing significant medical conditions